This invention relates to a hand held pen-size calculator having a writing head for entering data as they are being written on a writing surface.
In known pocket size calculators, data are entered by way of a keyboard. Such an arrangement, however, does not allow extreme miniaturization and cost reduction to be achieved for two reasons:
(1) keyboard design seems to have reached its minimum size and it will not be possible to go substantially further in miniaturization without impeding the easy actuation of the keys with the fingers of the hand; PA1 (2) the relative mechanical complexity of the keyboard assembly.
Some attempts have been made to devise a writing instrument capable of generating a code signal indicative of a character as it is being written on a writing surface.
Besides several attempts that have devised a writing instrument requiring that the characters be written on a surface which has been subjected to a special treatment, there are others which permit a character recognition signal to be generated as the character is being written on any writing surface whatsoever. Such an apparatus is disclosed in U.S. Pat. No. 3,835,453. This apparatus comprises a contact arm having a portion which is mounted so that it is capable of pivotal movement in response to the rotation of a writing ball, the contact arm, as the writing ball is moved across the writing surface, being pivoted into contacting engagement with predetermined ones of a plurality of contact ends. This apparatus is constructed such that it generates character identification signals as the writing ball is moved in any direction across the writing surface provided the apparatus is held at an angular position with respect to the writing surface. This apparatus in itself is an improvement as compared to previous proposals in that it permits the calculating time to be reduced, for there is no need to actuate keys on a keyboard for entering the data and in that the apparatus is more convenient to use because the data are entered as they are simply being written on a writing surface. Furthermore, a written trace of the calculations still remains for later checking, which advantage is only provided with a more bulky and more expensive apparatus having a printing device. However, the contact arrangement in this apparatus appears to be rather unreliable when used at a small angular position with respect to the normal to the writing surface due to the lateral forces which occur and are applied to the contact arrangement as a character is being written. Further, this apparatus is not suitable for use in a hand held calculator for it is intended to operate in cooperation with a distant receiving apparatus including a code recognition network.
In all the attempts known so far a primary problem still remains unsolved. In effect, in these attempts it is necessary that the characters be written in a predetermined way. That is, these apparatus are not capable of recognizing any character as it is actually written by the user in its own very specific hand.
The invention solves this problem by providing an apparatus capable of storing the hand-writing of the user thereby guaranteeing the univocal recognition of the written characters as they are usually written by the user and to allow the user's hand writing to be stored.